Method and Apparatus For Data Packet Transport In a Wireless Communication System Using an Internet Protocol

ABSTRACT

Method and apparatus for data packet transport in a wireless transmission system supporting broadcast transmissions. A multicast tree is built between nodes through neighboring routers. The multicast tree forms a tunnel through which the broadcast content is transmitted. The broadcast message is encapsulated in an Internet Protocol packet for transmission through the multicast tree. At least one multicast tree is formed between the Internet portion of the system and the wireless portion of the system, such as the Access Network. In one embodiment, an external multicast tree is formed between a content source and a packet data service node, and an internal multicast tree is formed between the packet data service node and a packet control function node.

CLAIM OF PRIORITY UNDER 35 U.S.C. 120

The present application for patent is a Division of and claims priorityto patent application Ser. No. 09/970,487 filed Oct. 3, 2001 entitled“Method and Apparatus for Data Packet Transport in a WirelessCommunication System Using an Internet Protocol” assigned to theassignee hereof and hereby expressly incorporated by reference, nowallowed.

REFERENCE TO CO-PENDING APPLICATIONS FOR PATENT

The present invention is related to the following applications forpatent in the U.S. Patent & Trademark Office:

-   -   “Method and Apparatus for Data Transport in a Wireless        Communication System” by Raymond Hsu, having Attorney Docket No.        010499, now U.S. Pat. No. 6,707,801.

BACKGROUND

1. Field

The present invention relates to wireless communication systemsgenerally and specifically, to methods and apparatus for messagecompression in preparation for transmission in a wireless communicationsystem.

2. Background

There is an increasing demand for packetized data services over wirelesscommunication systems. As traditional wireless communication systems aredesigned for voice communications, the extension to support dataservices introduces many challenges. The conservation of bandwidth isthe overwhelming concern for most designers. In uni-directiontransmissions, such as broadcast transmissions, a single broadcastcontent is provided to multiple users. The users are identified by aunique identifier which is then included in addressing information. Insuch a system, multiple infrastructure elements may be required toduplicate the broadcast packets so as to identify each of the multipleintended receivers. The duplication of transmission signals uses upvaluable bandwidth thus reducing the efficiency of the communicationsystem, and increases the processing requirements of intermediateinfrastructure elements. For a broadcast service in particular, thenumber of target recipients may be prohibitively large, thus creatingproblems of resource allocation and loss of available bandwidth.

There is a need, therefore, for an efficient and accurate method oftransmitting data to multiple recipients in a wireless communicationsystem. Further, there is a need for a method of routing broadcast datato multiple users, wherein each user is uniquely identified as a targetrecipient.

SUMMARY

Embodiments disclosed herein address the above stated needs by providinga method for routing IP packets in a wireless communication system,wherein packets are routed to the Access Network using a multicastaddress.

In one aspect, a communication path for processing broadcast messages ina wireless communication system, includes a first multicast treeportion, wherein the broadcast message is transmitted addressed to amulticast Internet Protocol address, a second multicast tree portion,wherein the broadcast message is transmitted addressed to a multicastInternet Protocol address, and a third portion, wherein the broadcastmessage is transmitted addressed to at least one unicast address.

In another aspect, In a wireless communication system supportingbroadcast transmissions, the system having a broadcast source node andat least one termination node, at least one router coupled between thesource node and the at least one termination node, a method for settingup transmission paths includes determining a transmission range for abroadcast transmission within the system, building a multicast tree froma first termination node to the broadcast source node, the multicasttree including the at least one router, and transmitting a broadcastmessage through the multicast tree over the transmission range.

In still another aspect, an infrastructure element for generatingInternet Protocol packets in a wireless transmission system supportingbroadcast transmissions, the infrastructure element includes means fordetermining a broadcast transmission range, means for generating anInternet Protocol packet, the Internet Protocol packet having amulticast address, and means for transmitting the Internet Protocolpacket.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a spread spectrum communication system thatsupports a number of users.

FIG. 2 is a block diagram of the communication system supportingbroadcast transmissions.

FIG. 3 is a model of the protocol stack corresponding to a broadcastservice option in a wireless communication system.

FIG. 4 is a flow diagram for a message flow for broadcast service in awireless communication system topology.

FIG. 5 is a functional diagram of a wireless communication systemsupporting broadcast transmission with multicast Internet Protocoltransmission of broadcast content.

FIG. 6 is an architectural diagram of a multicast tree structureapplicable to a communication system.

FIG. 7 is a flow diagram of broadcast processing in a wirelesscommunication system incorporating multicast Internet Protocoltransmissions.

FIG. 8 is a flow diagram of a process for building a multicast tree in acommunication system.

FIG. 9A is a flow diagram of multicast processing of a broadcast messagein a wireless communication system.

FIG. 9B is a signal flow diagram of setting up a data path in a wirelesscommunication system using a multicast Internet Protocol.

FIG. 10 is a flow diagram of multicast processing of a broadcast messagein a wireless communication system.

FIG. 11A is a flow diagram of multicast processing of a broadcastmessage in a wireless communication system.

FIG. 11B is a signal flow diagram of broadcast processing in a wirelesscommunication system using a multicast Internet Protocol.

FIG. 12 is a flow diagram for a message flow for a group call service ina wireless communication system topology.

DETAILED DESCRIPTION

The word “exemplary” is used exclusively herein to mean “serving as anexample, instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

The efficient use of available bandwidth impacts the performance andbreadth of the system. Toward that end, various techniques have beenapplied to reduce the size of overhead information transmitted alongwith the data or content information. For example, in a digitaltransmission, data is transmitted in frames. A frame of informationtypically includes header information, data payload information, and atail portion. The frames may be part of a packet of data, part of a datamessage, or continuous frames in a stream of information, such as audioand/or video streams. Attached to each frame of data (and each packet ormessage) is a header containing processing information that allows thereceiver to understand the information contained in the frame(s). Thisheader information is considered overhead, i.e., processing informationtransmitted along with information content. The information content isreferred to as the payload.

The data frames are transmitted throughout the communication system viavarious infrastructure elements. In a conventional system, thetransmission of information to multiple users requires the duplicationof the information at a central packet data control point, such as aPacket Data Service Node (PDSN). The duplication increases theprocessing requirements of the PDSN and wastes valuable bandwidth. Forexample, expansion of a given system may require routers and trunksproximate a PDSN be sized sufficiently to handle the duplicated traffic.The PDSN transmits the multiple copies to the base stations, whichforward the information to each user. The conventional approach isparticularly disadvantageous in a uni-directional broadcast service,wherein many users are receiving the broadcast transmission. The PDSN inthis case must make a great number of copies, apply a specific addressto each copy and transmit the copies individually.

The PDSN is typically required to provide additional header informationidentifying each target recipient. For a broadcast service, the numberof target recipients may be prohibitively large, thus creating problemsof resource allocation and loss of available bandwidth.

An exemplary embodiment of a wireless communication system employs amethod of data transport that reduces the bandwidth used by theinfrastructure elements while satisfying the accuracy and transmissionrequirements of the system. In the exemplary embodiment, duplication isperformed at the BS or Packet Control Function (PCF) node, freeing thePDSN or central packet data router, to send the message with amulti-cast header to each BS or PCF involved in the broadcast. Forexample, a message may process through a MC tree to a PCF, wherein thePCF duplicates the message for each BSC and then transmits each messagevia a distinct Uni-Cast (UC) connection, i.e., connection or securetunnel created between the PCF and a specific BSC. Note that a UCconnection may be considered a point-to-point connection. The exemplaryembodiment supports a uni-directional broadcast service. The broadcastservice provides video and/or audio streams to multiple users.Subscribers to the broadcast service “tune in” to a designated channelto access the broadcast transmission. As the bandwidth requirement forhigh speed transmission of video broadcasts is great, it is desirable toreduce the amount of duplication and transmission of duplicate packetsover the hops in the network.

The following discussion develops the exemplary embodiment by firstpresenting a spread-spectrum wireless communication system generally.Next, the broadcast service is introduced; wherein the service isreferred to as High Speed Broadcast Service (HSBS), and the discussionincludes channel assignments of the exemplary embodiment. A subscriptionmodel is then presented including options for paid subscriptions, freesubscriptions, and hybrid subscription plans, similar to those currentlyavailable for television transmissions. The specifics of accessing thebroadcast service are then detailed, presenting the use of a serviceoption to define the specifics of a given transmission. The message flowin the broadcast system is discussed with respect to the topology of thesystem, i.e., infrastructure elements. Finally, the header compressionused in the exemplary embodiment is discussed

Note that the exemplary embodiment is provided as an exemplar throughoutthis discussion; however, alternate embodiments may incorporate variousaspects without departing from the scope of the present invention.Specifically, the present invention is applicable to a data processingsystem, a wireless communication system, a uni-directional broadcastsystem, and any other system desiring efficient transmission ofinformation.

Wireless Communication System

The exemplary embodiment employs a spread-spectrum wirelesscommunication system, supporting a broadcast service. Wirelesscommunication systems are widely deployed to provide various types ofcommunication such as voice, data, and so on. These systems may be basedon code division multiple access (CDMA), time division multiple access(TDMA), or some other modulation techniques. A CDMA system providescertain advantages over other types of system, including increasedsystem capacity.

A system may be designed to support one or more standards such as the“TIA/EIA/IS-95-B Mobile Station-Base Station Compatibility Standard forDual-Mode Wideband Spread Spectrum Cellular System” referred to hereinas the IS-95 standard, the standard offered by a consortium named “3rdGeneration Partnership Project” referred to herein as 3GPP, and embodiedin a set of documents including Document Nos. 3G TS 25.211, 3G TS25.212, 3G TS 25.213, and 3G TS 25.214, 3G TS 25.302, referred to hereinas the W-CDMA standard, the standard offered by a consortium named “3rdGeneration Partnership Project 2” referred to herein as 3GPP2, andTR-45.5 referred to herein as the cdma2000 standard, formerly calledIS-2000 MC. The standards cited hereinabove are hereby expresslyincorporated herein by reference.

Each standard specifically defines the processing of data fortransmission from base station to mobile, and vice versa. As anexemplary embodiment the following discussion considers aspread-spectrum communication system consistent with the cdma200standard of protocols. Alternate embodiments may incorporate anotherstandard. Still other embodiments may apply the compression methodsdisclosed herein to other types of data processing systems.

FIG. 1 serves as an example of a communications system 100 that supportsa number of users and is capable of implementing at least some aspectsand embodiments of the invention. Any of a variety of algorithms andmethods may be used to schedule transmissions in system 100. System 100provides communication for a number of cells 102A through 102G, each ofwhich is serviced by a corresponding base station 104A through 104G,respectively. In the exemplary embodiment, some of base stations 104have multiple receive antennas and others have only one receive antenna.Similarly, some of base stations 104 have multiple transmit antennas,and others have single transmit antennas. There are no restrictions onthe combinations of transmit antennas and receive antennas. Therefore,it is possible for a base station 104 to have multiple transmit antennasand a single receive antenna, or to have multiple receive antennas and asingle transmit antenna, or to have both single or multiple transmit andreceive antennas.

Terminals 106 in the coverage area may be fixed (i.e., stationary) ormobile. As shown in FIG. 1, various terminals 106 are dispersedthroughout the system. Each terminal 106 communicates with at least oneand possibly more base stations 104 on the downlink and uplink at anygiven moment depending on, for example, whether soft handoff is employedor whether the terminal is designed and operated to (concurrently orsequentially) receive multiple transmissions from multiple basestations. Soft handoff in CDMA communications systems is well known inthe art and is described in detail in U.S. Pat. No. 5,101,501, entitled“Method and system for providing a Soft Handoff in a CDMA CellularTelephone System”, which is assigned to the assignee of the presentinvention.

The downlink refers to transmission from the base station to theterminal, and the uplink refers to transmission from the terminal to thebase station. In the exemplary embodiment, some of terminals 106 havemultiple receive antennas and others have only one receive antenna. InFIG. 1, base station 104A transmits data to terminals 106A and 106J onthe downlink, base station 104B transmits data to terminals 106B and106J, base station 104C transmits data to terminal 106C, and so on.

Increasing demand for wireless data transmission and the expansion ofservices available via wireless communication technology have led to thedevelopment of specific data services. One such service is referred toas High Data Rate (HDR). An exemplary HDR service is proposed in“EIA/TIA-IS856 cdma2000 High Rate Packet Data Air InterfaceSpecification” referred to as “the HDR specification.” HDR service isgenerally an overlay to a voice communication system that provides anefficient method of transmitting packets of data in a wirelesscommunication system. As the amount of data transmitted and the numberof transmissions increases, the limited bandwidth available for radiotransmissions becomes a critical resource. There is a need, therefore,for an efficient and fair method of scheduling transmissions in acommunication system that optimizes use of available bandwidth. In theexemplary embodiment, system 100 illustrated in FIG. 1 is consistentwith a CDMA type system having HDR service.

High Speed Broadcast System (HSBS)

A wireless communication system 200 is illustrated in FIG. 2, whereinvideo and audio information is provided to Packet Data Service Node(PDSN) 202. The video and audio information may be from televisedprogramming or a radio transmission. The information is provided aspacketized data, such as in IP packets. The PDSN 202 processes the IPpackets for distribution within an Access Network (AN). As illustratedthe AN is defined as the portions of the system including a BS 204 incommunication with multiple MS 206. The PDSN 202 is coupled to the BS204. For HSBS service, the BS 204 receives the stream of informationfrom the PDSN 202 and provides the information on a designated channelto subscribers within the system 200.

In a given sector, there are several ways in which the HSBS broadcastservice may be deployed. The factors involved in designing a systeminclude, but are not limited to, the number of HSBS sessions supported,the number of frequency assignments, and the number of broadcastphysical channels supported.

The HSBS is a stream of information provided over an air interface in awireless communication system. The “HSBS channel” to refer to a singlelogical HSBS broadcast session as defined by broadcast content. Notethat the content of a given HSBS channel may change with time, e.g., 7am News, 8 am Weather, 9 am Movies, etc. The time based scheduling isanalogous to a single TV channel. The “Broadcast channel” refers to asingle forward link physical channel, i.e., a given Walsh Code, thatcarries broadcast traffic. The Broadcast Channel, BCH, corresponds to asingle Code Division Multiplex (CDM) channel.

A single broadcast channel can carry one or more HSBS channels; in thiscase, the HSBS channels will be multiplexed in a Time-Division Multiplex(TDM) fashion within the single broadcast channel. In one embodiment, asingle HSBS channel is provided on more than one broadcast channelwithin a sector. In another embodiment, a single HSBS channel isprovided on different frequencies to serve subscribers in thosefrequencies.

According to the exemplary embodiment, the system 100 illustrated inFIG. 1 supports a high-speed multimedia broadcasting service referred toas High-Speed Broadcast Service (HSBS). The broadcast capabilities ofthe service are intended to provide programming at a data ratesufficient to support video and audio communications. As an example,applications of the HSBS may include video streaming of movies, sportsevents, etc. The HSBS service is a packet data service based on theInternet Protocol (IP).

According to the exemplary embodiment, a Content Server (CS) advertisesthe availability of such high-speed broadcast service to the systemusers. Any user desiring to receive the HSBS service may subscribe withthe CS. The subscriber is then able to scan the broadcast serviceschedule in a variety of ways that may be provided by the CS. Forexample, the broadcast schedule may be communicated throughadvertisements, Short Management System (SMS) messages, WirelessApplication Protocol (WAP), and/or some other means generally consistentwith and convenient for mobile wireless communications. Mobile users arereferred to as Mobile Stations (MSs). Base Stations (BSs) transmit HSBSrelated parameters in overhead messages, such as those transmitted onchannels and/or frequencies designated for control and information,i.e., non-payload messages. Payload refers to the information content ofthe transmission, wherein for a broadcast session the payload is thebroadcast content, i.e., the video program, etc. When a broadcastservice subscriber desires to receive a broadcast session, i.e., aparticular broadcast scheduled program, the MS reads the overheadmessages and learns the appropriate configurations. The MS then tunes tothe frequency containing the HSBS channel, and receives the broadcastservice content.

The channel structure of the exemplary embodiment is consistent with thecdma2000 standard, wherein the Forward Supplemental Channel (F-SCH)supports data transmissions. One embodiment bundles a large number ofthe Forward Fundamental Channels (F-FCHs) or the Forward DedicatedControl Channels (F-DCCHs) to achieve the higher data rate requirementsof data services. The exemplary embodiment utilizes an F-SCH as thebasis for the F-BSCH supporting a payload of 64 kbps (excluding RTPoverhead). The F-BSCH may also be modified to support other payloadrates, for example, by subdividing the 64-kbps payload rate intosub-streams of lower rates.

One embodiment also supports group calls in several different ways. Forexample, by using existing unicast channels, i.e., one forward linkchannel per MS with no sharing, of F-FCH (or the F-DCCH) on both forwardand reverse links. In another example, the F-SCH (shared by groupmembers in the same sector) and the F-DCCH (no frames but the ForwardPower Control Subchannel most of the time) on the forward link and theR-DCCH on the reverse link are applied. In still another example, thehigh-rate F-BSCH on the forward link and the Access Channel (or theEnhanced Access Channel/Reverse Common Control Channel combination) onthe reverse link is utilized.

Having a high data rate, the Forward Broadcast Supplemental CHannel(F-BSCH) of the exemplary embodiment may use a very large portion of abase station's forward link power to provide adequate coverage. Thephysical layer design of HSBC is thus focused on efficiency improvementsin a broadcast environment.

To provide adequate support for video services, system design considersthe required base station power for various ways to transmit the channelas well as the corresponding video quality. One aspect of the design isa subjective trade-off between the perceived video quality at the edgeof coverage and that close to the cell site. As the payload rate isreduced, the effective error correcting code rate is increased, a givenlevel of base station transmit power would provide better coverage atthe edge of the cell. For mobile stations located closer to the basestations, the reception of the channel remains error-free and the videoquality would be lowered due to the lowered source rate. This sametrade-off also applies to other, non-video applications that the F-BSCHcan support. Lowering the payload rate supported by the channelincreases the coverage at the expense of decreased download speed forthese applications. The balancing the relative importance between videoquality and data throughput versus coverage is objective. Theconfiguration chosen seeks an application-specific optimizedconfiguration, and a good compromise among all possibilities.

The payload rate for the F-BSCH is an important design parameter. Thefollowing assumptions may be used in designing a system supportingbroadcast transmissions according to the exemplary embodiment: (1) thetarget payload rate is 64 kbps, which provides an acceptable videoquality; (2) for streaming video services, the payload rate is assumedto include the 12 8-bit bytes per packet overhead of the RTP packets;(3) the average overhead for all layers between RTP and the physicallayer is approximately 64, 8-bit bytes per packet plus 8 bits per F-SCHframe overhead used by the MUXPDU header.

In the exemplary embodiment, for non-video broadcast services, themaximum rate supported is 64 kbps. However, many other possible payloadrates below 64 kbps are also achievable.

Subscription Models

There are several possible subscription/revenue models for HSBS service,including free access, controlled access, and partially controlledaccess. For free access, no subscription is needed by the to receive theservice. The BS broadcasts the content without encryption and interestedmobiles can receive the content. The revenue for the service providercan be generated through advertisements that may also be transmitted inthe broadcast channel. For example, upcoming movie-clips can betransmitted for which the studios will pay the service provider.

For controlled access, the MS users subscribe to the service and pay thecorresponding fee to receive the broadcast service. Unsubscribed usersare not being able to receive the HSBS service. Controlled access can beachieved by encrypting the HSBS transmission/content so that only thesubscribed users can decrypt the content. This may use over-the-airencryption key exchange procedures. This scheme provides strong securityand prevents theft-of-service.

A hybrid access scheme, referred to as partial controlled access,provides the HSBS service as a subscription-based service that isencrypted with intermittent unencrypted advertisement transmissions.These advertisements may be intended to encourage subscriptions to theencrypted HSBS service. Schedule of these unencrypted segments could beknown to the MS through external means.

HSBS Service Option

The HSBS service option is defined by: (1) a protocol stack; (2) optionsin the protocol stack; and (3) procedures for setting up andsynchronizing the service. The protocol stack according to the exemplaryembodiment is illustrated in FIGS. 3 and 4. As illustrated in FIG. 3,the protocol stack is specific to the infrastructure element, i.e., MS,BS, PDSN and CS in the exemplary embodiment.

Continuing with FIG. 3, for the application layer of the MS, theprotocol specifies audio codec, visual codec, as well as any visualprofiles. Additionally, the protocol specifies Radio Transport Protocol(RTP) payload types when RTP is used. For the transport layer of the MS,the protocol specifies a User Datagram Protocol (UDP) port. The securitylayer of the MS is specified by the protocol, wherein securityparameters are provided via out-of-band channels when the security isinitially associated with the CS. The network layer specifies the IPheader compression parameters. According to one embodiment, at the linklayer, data packets are compressed and then an appropriate framingprotocol is applied to the compressed data.

Message Flow

FIG. 4 illustrates the call flow of one embodiment for a given systemtopology. The system includes a MS, BS, PDSN and CS, as listed on thehorizontal axis. The vertical axis represents the time. The user or MSis a subscriber to the HSBS service. At time t1 the MS and CS negotiatethe subscription security for the broadcast service. Negotiationinvolves exchange and maintenance of encryption keys, etc., used forreceiving the broadcast content on the broadcast channel. The userestablishes a security association with the CS on reception of theencryption information. The encryption information may include aBroadcast Access Key (BAK) or a key combination, etc., from the CS.According to one embodiment, the CS provides the encryption informationover a dedicated channel during a packet data session, such as via PPP,WAP, or other out-of-band methods.

At time t2 the MS tunes into the broadcast channel and starts to receivepackets. At this point in time, the MS is unable to process the receivedpackets because the IP/ESP header is compressed via ROHC, and the MS'sdecompressor has not been initialized. The PDSN provides headercompression information (detailed hereinbelow) at time t3. From the ROHCpacket header, the MS detects and obtains a ROHC Initialization &Refresh (IR) packet sent periodically from the PDSN to the broadcastchannel. The ROHC IR packet is used to initialize the state ofdecompressor in the MS, allowing it to decompress the IP/ESP header ofthe received packets. The MS is then able to process the IP/ESP headerof the received packets, however, the MS requires further information toprocess the ESP payload as the payload is encrypted with a Short-termKey (SK) at the CS. The SK acts in coordination with the BAK, whereinthe SK is decrypted at the receiver using the BAK. The CS providesfurther encryption information, such as updated key information or acurrent SK at time t4. Note that the CS provides this informationperiodically to the MS to ensure the ongoing security of the broadcast.At time t5 the MS receives the broadcast content from the CS. Note thatalternate embodiments may incorporate alternate compression anddecompression methods that provide efficient transmission of the headerinformation. Additionally, alternate embodiments may implement a varietyof security schemes to protect the broadcast content. Still alternateembodiments may provide a non-secure broadcast service. The MS uses theencryption information, such as the SK, to decrypt and display broadcastcontent.

Access Network

A general access network topology for a system 300 is illustrated inFIG. 5 having a CS 326, two PDSN 320, 322, a PCF 310, a co-located PCFand BSC 312, and three BSC 302, 304, 306. The CS 326 is coupled to thePDSN 320, 322 by way of an IP cloud 324. The IP cloud 324, as well as IPclouds 314 and 308 are basically a configuration of interconnectedrouters that form an IP path from the CS to various recipients of datafrom the CS. In the IP cloud 308 a virtual tunnel, referred to as an A8tunnel, is formed for transmitting information from the PCF 310 to theBSC 302 and the BSC 304. The tunnel may be a GRE tunnel. A protocolreferred to as A9 is used for establishing the A8 tunnel. The IP cloud308 may be labeled an A8/A9 cloud. In the IP cloud 314 a virtual tunnel,referred to as an A10 tunnel, is formed for transmitting informationfrom the PDSN 320 to each of the PCF 310 and the PCF/BSC 312. Note thatan A10 tunnel is formed from PDSN 320 to PCF 310 and a second A10 tunnelis formed from PDSN 320 to PCF/BSC 312. The tunnels may be GRE tunnels.A protocol referred to as A11 is used for establishing the A10 tunnel.The IP cloud 314 may be labeled an A10/A11 cloud. One embodiment isconsistent with that specified in the cdma2000 and HDR standards,described hereinabove. The Access Network (AN) is defined as theelements and connections from the PDSN to the end user, e.g., MS.

According to one embodiment, the broadcast CS 326 sends IP packetscontaining encrypted broadcast content to a multicast group identifiedby a class-D multicast IP address. This address is used in thedestination address field of the IP packets. A given PDSN 320participates in multicast routing of these packets. After compression,the PDSN 320 places each packet in an HDLC frame for transmission. TheHDLC frame is encapsulated by a Generic Routing Encapsulation (GRE)packet. Note that the GRE encapsulation forms the A10 tunnel describedhereinabove. The key field of the GRE packet header uses a special valueto indicate a broadcast bearer connection. The GRE packet is appendedwith the 20-byte IP packet header having a source address fieldidentifying the IP address of the PDSN 320, and destination addressfield uses a class-D multicast IP address. The multicast IP address isthe same as the one used by the original IP packet from CS 326. Thepackets delivered in the broadcast connection are provided in sequence;in one embodiment the GRE sequencing feature is enabled. Duplication ofthe IP multicast packets is done in multicast-capable routers. Note thataccording to an alternate embodiment, the IP cloud 314 implementspoint-to-point, or uni-cast, tunnels to individual recipient PCF(s). Thedecision to us a multicast link or a unicast link for this connectionpoint is made at a higher layer, wherein the UC tunnels provideincreased security, and the MC tree provides efficiency.

According to an exemplary embodiment, the CS 326 transmits data to thePDSN 320 via a multicast IP address, wherein the PDSN 320 furthertransmits data to the PCF 310 and the PCF/BSC 312 also via a multicastIP address. The PCF 310, for example, then determines the number ofindividual users in the active set that are in the destinationsubscription group and duplicates the frame received from the CS 326 foreach of those users. The PDSN PCF 310 determines the BSC(s)corresponding to each of the users in the subscription group.

In one embodiment, the BSC 304 is adapted to transmit to proximateBSC(s), wherein the BSC 304 may duplicate the received packets and sendthem to one or more of the neighboring BSC(s). The chaining of BSCsyields better soft handoff performance. The “anchoring” BSC methodyields better soft handoff performance. The anchoring BSC 304 duplicatesthe transmission frame and sends it with the same time-stamp to itsneighboring BSCs. The time-stamp information is critical to the softhandoff operation as the mobile station receives transmission framesfrom different BSCs.

Multi-Cast Service

One type of broadcast service is referred to as MultiCast (MC) serviceor “Group Call (GC)” wherein a “GC group” includes those users that willbe participants in the GC, wherein a group of users is identified for agiven MC content. The group of users may be referred to as a MC group.The MC content is intended only for the MC group members. Each activeuser in the MC group registers with the AN. The AN then tracks thelocation of each registered user, and targets transmission of the MCmessage to these locations. Specifically, the AN determines a cell,sector, and/or geographical area within which each of the users of theMC group is located, and then transmits the message to PCFs associatedwith those cells, sectors, and/or geographic areas.

As opposed to some other type broadcast services wherein the BC messageis transmitted without knowledge of the location and activity of therecipients or subscribers, the MC service operates using knowledge ofthe active users, specifically the location of each active user.Additionally, the users provide location information to the AN. In oneembodiment the active users in an MC group register with the AN via IPcommunications, specifically by using an Internet Group ManagementProtocol (IGMP) message. As the MC service is able to identify thelocation of each user, and the MC targets transmission to thoselocations, the MC service utilizes a router between the PCF(s) and thePDSN(s). The MC service builds a tree of connections that provide a pathfrom the CS to each PCF that is communicating with an active user in theMC group. The tree is referred to as an MC tree; an example of an MCtree is illustrated in FIG. 6 and is discussed hereinbelow.

In a conventional IP network or system, such as a computer networkcoupled to the Internet, if a user desires to receive MC typeinformation, referred to as the MC content, the user registers with thenearest router using the Internet Group Management Protocol (IGMP). Therouter then begins the process of building a MC tree by registering withthe next adjacent router. The CS then sends MC content in the form of aMC IP packet. The MC IP packet is then routed through the MC tree to theoriginal router. This router duplicates the data for each user desiringthe MC content. A common broadcast media in a computer network is anEthernet hub that connects multiple users to a same information stream.

The combination of the Internet and IP networks with wirelesscommunication systems introduces several distinct problems. One problemis routing the information from the IP network through the wirelessnetwork. Several of the interconnections are predefined in a wirelesssystem. For example, as discussed hereinabove, the interface between theBSC and PCF is defined by the A8/A9 connection. Similarly, the PCF toPDSN connection is defined by the A10/A11 connection. One embodimentforms an internal MC tree between the PDSN and PCF, and forms anexternal MC tree between the PDSN and the CS. The PCF then formsspecific tunnels to the various BSCs that request the MC content. Thisembodiment, discussed hereinbelow, provides efficiency of operation.Another embodiment forms the external MC tree between the PDSN and theCS, while setting up tunnels from the PDSN to each individual PCF thatis to receive the MC content. This embodiment provides securecommunications.

Generally, the MC path is considered end-to-end, wherein the MC contentoriginates at a source and is transmitted to the end user. The end usermay be MS. Alternatively, the MS may be a mobile router that routes theMC content to a network. The end user does not forward the MC content.Note that a MC path may include a plurality of different types ofinterconnects. For example, one embodiment may incorporate the internalMC tree discussed hereinabove having a termination point at the PCF, andthe external MC tree having a termination point at the PDSN. Similarly,the MC path may include point-to-point tunnels, wherein each tunnel isformed between one node and a distinct individual node.

According to an exemplary embodiment illustrated in FIG. 5, acommunication system 300 includes a CS 326 in communication with PDSNs320 and 322 via an IP cloud 324. Note that CS 326 also communicates withother PDSNs not shown. The IP cloud 324 includes a configuration ofrouters, such as multicast routers (as described hereinabove) and otherrouters for passing data transmissions through the cloud 324.Transmissions through the IP cloud 324 are IP communications. Therouters within the IP cloud 324 accesses communications, such as BCmessages and MC messages, to target recipients consistent with theInternet Engineering Task Force (IETF) protocols.

Continuing with FIG. 5, the PDSN 320 and 322 are in communication withPCFs 310 and 312, as well as other PCFs not shown, via another IP cloud314. The IP cloud 314 includes a configuration of routers, such asmulticast routers and other routers for passing data transmissionsthrough the cloud 314. Transmissions through the IP cloud 314 are IPcommunications. The routers within the IP cloud 314 accessescommunications, such as BC messages and MC messages, to targetrecipients consistent with the Internet Engineering Task Force (IETF)protocols. Further, the PCF 310 communicates with the BSC 304 via stillanother IP cloud 308. The IP cloud 314 includes a configuration ofrouters, such as Multicast routers and other routers for passing datatransmissions through the cloud 314. Transmissions through the IP cloud314 are IP communications. The PCF 312 also operates as a BSC and is incommunication with any of the users within system 300 (not shown). Notethat for clarity three BSCs are illustrated, specifically, BSCs 302, 304and 306. The system 300 may include any number of additional BSC (notshown). Note that alternate embodiments may incorporate alternateconfigurations, wherein any or connections indicated by the multiple IPclouds, such as IP clouds 308, 314, 324, may be replaced withpoint-to-point connections. A point-to-point connection may be a secureconnection made between the apparatus at one point, such as at a PCF, toanother point, such as a BSC. The point-to-point connection is achievedover an IP cloud, such as IP cloud 308, using the method calledtunneling. The basic idea of tunneling to take an IP packet, encapsulatethe packet in GRE/IP and send the resultant packet to a destinationpoint. If the destination address of the outer IP header is a unicast IPaddress, the process achieves a point-to-point tunnel. If thedestination address is a multicast IP address, the process achieves apoint-to-multipoint tunnel. Note that all these are done in the same IPcloud. For example, in IP cloud 314, there are several differentapplicable methods. One method forms a point-to-point tunnel, and asecond method forms a point-to-multipoint tunnel. This is contrastedwith the connection method used in cloud 324, wherein no GRE tunnelingis used and the original multicast IP packet is transmitted.

In the exemplary embodiment, the CS 326 configures an HSBS channel withknowledge of a multicast IP address to be used in the IP cloud 324. TheCS uses the MC IP address to send the HSBS content information, referredto as the payload. Note that the configuration of FIG. 8 may be used tobroadcast a variety of BC services.

To form a tunnel, the message is encapsulated within an external IPpacket. As the encapsulated message transmits through the tunnel, theinternal IP address, i.e., IP address of the original IP packet, isignored. The encapsulation changes the Internet routing of the originalIP packet. In the exemplary embodiment, the MC tunnel routes the BC orMC message through the MC tree between PDSN and PCF.

In the exemplary embodiment, the PDSN 320 and the PCFs 310 and 312 areassociated with an MC group. In other words, MC group members arelocated within cells, sectors, and/or geographical areas serviced by thePCFs 310 and 312. The system 300 builds an external MC tree from the CS326 to the PDSN 320 and an internal tree from the PDSN 320 to PCFs 310and 312. The PDSN 320 builds the external MC tree by successivelyregistering with neighboring Multicast routers within the IP cloud 324.The external MC tree is built from the PDSN 320 to the CS 326 throughthe IP network. The PDSN 320 receives the MC message(s) for MC groupmembers via the external MC tree. In other words, MC messages are sentthrough the external MC tunnel structured by the external MC tree. Eachof the PCFs 310 and 312 builds an internal MC tree to the PDSN 320through the IP cloud 314. The MC message(s) from the PDSN 320 are sentover an internal MC tree in a GRE/IP tunnel.

FIG. 6 illustrates a MC tree 400 having a source 402 and multiplerouters 404 to 450. The source 402 is the base of the MC tree 400. Theend users 412, 414, 420, 422, 424, 434, and 450 are considered leaves ofthe MC tree 400. Two main branches are formed via routers 404 and 406.On the first main branch is another branch through router 410. On thesecond main branch are two subsequent branches: one through 430 andanother through 432.

In one embodiment, the tree 400 has a CS as a source. For a broadcastservice wherein the broadcast message originates at the CS, the source402 is a CS. In an alternate embodiment, the source may be anotherapparatus in the network. For example, for a group call service themessage content may originate with another user, wherein the BSCassociated with that user is the source of the MC tree. Additionally,there may be a group call manager function in the network that receivesmessages from a member then forwards the messages through the MC tree tothe Group Call members. In each of these cases, the tree provides apathway for providing same information content to multiple users whileconserving bandwidth and avoiding redundant duplication and processingof information.

FIG. 7 illustrates a method 500 for processing BC messages according toone embodiment. The process 500 builds a MC tree between at least oneBSC and a PCF. The tree may include multiple BSCs. Similarly, additionaltrees may be built for additional PCFs. The MC tree forms a path forsending a BC message to multiple recipients without setting uppoint-to-point connections. The process 500 also builds a MC treebetween at least one PCF and a PDSN. The tree may include multiple PCFsand one PDSN, wherein according to one embodiment, one internalmulticast tree may flow through only one PDSN, i.e., there is only onebase per tree). Additionally, the process 500 builds another MC treebetween at least one PDSN and a CS. The tree may include multiple PDSNs.

The broadcast service of the embodiment illustrated in FIG. 7 is thebroadcast of a BC message to a transmission range. At a first step 502the process 500 determines the transmission range of cell(s), sector(s),and/or geographical area(s) for transmission of the BC message. Thetransmission range information is used to build an MC tree.Specifically, identification of the transmission range identifies theleaves of the MC tree. The MC tree is built from the leaves to the base.The BSC sends a broadcast indicator to the PCF at step 504. Thebroadcast indicator is a signaling message to alert the PCF that the BSCwants to receive the broadcast. The process then builds a firstconnection between the BSC(s) of the transmission range and theassociated PCF(s) at step 505. The connection is a GRE secure tunnelbetween each BSC and PCF pair. The process then builds a MC tree betweenthe PDSN and the PCF at step 506. The transmission range identifies thePCF(s) for BC transmission. Each PCF within the transmission rangeinitiates the MC tree by registering with a neighboring Multicastrouter. According to the exemplary embodiment, the process then buildsanother MC tree from the PDSN(s) to the CS at step 508. At step 510 theCS sends the BC message to the PDSN(s), wherein the BC message isencapsulated in a MC IP packet. The MC IP packet is addressed to the MCIP address and identifies the CS as the source of the packet. The MC IPpacket address indicates delivery to any of the PDSN in the MC treebetween the PDSN(s) and the CS. At step 512 the BC message traverses theMC trees. The BC message is then sent to the BSC via the secure tunnelor UC connection at step 513. The BSCs transmit the BC message to usersin respective coverage areas at step 514.

Note that at this point, to accommodate soft handoff, the receiving BSCmay be used as an anchor BSC to timestamp the BC message and thenforward it to neighboring BSC(s). In this way, the BC message istransmitted from multiple BSCs to a given user, allowing the user totransition to a better connection without losing the transmission.Additionally, the use of an anchor BSC provides efficiency as the PCFonly transmits the BC message to one BSC, but the message may beprovided to multiple other BSCs.

FIG. 8 illustrates the process 550 of building an MC tree from a PCF toa PDSN. At step 552 the PCF registers with the next neighboringMulticast router. The registration with the Multicast router initiates aregistration chain, wherein each member of the chain registered with thenext successive router. The registration with the Multicast routerfurther involves identifying the registering PCF as a member of a givenMC group and a target of any IP packets addressed to the MC IP addressof the MC group. Note that for a BC message, the MC group may beconsidered the target range. At decision diamond 554 if the Multicastrouter is registered, the process ends as the MC tree is complete. Ifthe Multicast router is not registered, i.e., not part of the MC tree,the Multicast router registers with the next successive neighboringMulticast router at step 556.

FIG. 9A illustrates the flow of a BC message through multiple MC trees,as described in the process 500 of FIGS. 7 and 8. FIG. 9B illustratesthe corresponding signal flow of information, i.e., broadcast messageprocessing. As illustrated in FIG. 9A, the BC message originates at theCS 326. The original message is considered the payload. The CS 326encapsulates the payload by applying a MC IP to generate a MC IP packet.The MC IP packet indicates the CS is the source of the packet and thedestination is given as the MC IP address. The MC IP packet is sent tothe next contacts on the tree. In other words, the MC IP packettraverses the tree from the source or base of the tree outward towardthe leaves. For clarity, a single PDSN is illustrated, specifically PDSN320, however, the MC tree may include any number of PDSNs eachidentified by the MC IP address. The PDSN 320, and any other PDSN in theMC tree, compress the MC IP packet and apply a framing protocol, such asHDLC, to form a Compressed Framed Packet (CFP). The CFP is thenencapsulated by a GRE protocol to form a GRE packet. The resulting GREpacket is further encapsulated according to a MC IP, resulting in a MCCFP, i.e., multicast compressed framed packet. The MC CFP identifies thePDSN 320 as the source and the MC IP address as the destination. In theexample illustrated in FIG. 9A, the PDSN 320 passes the MC CFP to PCFs310 and 312, each part of the MC tree. Each of PCFs 310 and 312processes the received MC to form secure tunnels to the BSC(s), such asto BSC 304, wherein the resultant packet is a UC BSC packet identifyingthe respective PCF as the source and the BSC IP address as thedestination. Note that each PCF may form multiple tunnels to individualBSCs. As illustrated, the MC IP addressing is used until the messagearrives at the PCF. From the PCF to the end user, this embodiment usessecure tunnels or UC connections.

FIG. 9B illustrates the corresponding signal flow, wherein the CSinitially sets up a HSBS channel. At time t1 the GRE tunnel is set upbetween the BSC and the PCF. At time t2 the PCF registers with theneighboring Multicast router using IGMP. At time t3 the PCF confirms theGRE tunnel set up with the BSC. At time t4 a MC Routing Protocol (MRP)is used to register Multicast routers between the PCF and the PDSN. Attime t5 the PDSN registers with the neighboring Multicast router. Theprocess forms the external portion of the MC tree. Each of the levels ofthe MC tree, i.e., CS to PDSN, and PDSN to PCF, may be considered anindividual MC tree or the entire structure from CS to PCF may beconsidered one tree. At this point the BSC is setup to receive BCmessages via MC IP from the BC CS for the given HSBS channel.

FIG. 10 illustrates an alternate embodiment of a process 700 fortransmitting a BC message. The process starts by determining thetransmission range of the broadcast at step 702. At step 704 a UCconnection is set up between the BSC and the PCF. The UC connection maybe an A8/A9 IP connection. Similarly, a UC connection is set up betweenthe PCF and the PDSN at step 706. In contrast to the process 500 of FIG.10, no MC tree is built between the PDSN(s) and PCF(s). Rather, apoint-to-point GRE Tunnel is formed to between each PDSN and PCF pair.The PDSN to PCF UC connection may be an A10/A11 IP connection. At step708, a MC tree is built between the CS and the PDSN.

The CS then sends data to the PDSN(s) that are part of the MC tree atstep 709. The data travels through the MC tree to the PDSN at step 710.The PDSN then processes the received data or BC message and forwards theBC message to the PCF at step 712. Note that when multiple PCFs areimplemented, the PDSN creates multiple copies of the data fortransmission to multiple PCFs. The PCF sends the data to the BSC via aUC connection at step 714. The data or BC message is then transmittedfrom the BSCs associated with the MC group to group members at step 716

FIG. 11A illustrates the flow of a BC message through multiple MC trees,as described in the process 700 of FIG. 10. FIG. 11B illustrates thecorresponding signal flow of information, i.e., broadcast messageprocessing. In contrast to process 500 of FIG. 7, the process 700 buildsa MC tree between the CS and the PDSN(s), but incorporatespoint-to-point secure tunnels between the PDSN(s) and PCF(s), as well asbetween the PCF(s) and individual BSC(s). The user of point-to-pointconnections provides additional security at the expense of processingand bandwidth considerations.

As illustrated in FIG. 11A, the BC message originates at the CS 326. Theoriginal message is considered the payload. The CS 326 encapsulates thepayload by applying a MC IP to generate a MC IP packet. The MC IP packetindicates the CS is the source of the packet and the destination isgiven as the MC IP address. The MC IP packet is sent to the nextcontacts on the tree. In other words, the MC IP packet traverses thetree from the source or base of the tree outward toward the leaves. Forclarity, a single PDSN is illustrated, specifically PDSN 320, however,the MC tree may include any number of PDSNs each identified by the MC IPaddress. The PDSN 320, and any other PDSN in the MC tree, compress theMC IP packet and apply a framing protocol, such as HDLC, to form aCompressed Framed Packet (CFP). The CFP is then encapsulated by a GREprotocol to form a GRE packet. The resulting GRE packet is furtherencapsulated according to a Uni-Cast (UC) IP, resulting in a UC CFP,i.e., uni-cast compressed framed packet. The UC CFP identifies the PDSN320 as the source and a specific PCF as the destination. In the exampleillustrated in FIG. 11A, the PDSN 320 passes the UC CFPs to PCFs 310 and312. Each of PCFs 310 and 312 processes the received UC CFP in a similarmanner to the PDSN 320, wherein the resultant packet is a UC BSC packetidentifying the respective PCF as the source and a BSC as thedestination.

FIG. 11B illustrates the corresponding signal flow, wherein the CSinitially sets up a HSBS channel. At time t1 the BSC sets up the GREtunnel between the BSC and the PCF. At time t2 the PCF PCF sets up GREtunnel between PCF and the PDSN. At time t3 the PDSN confirms the GREtunnel set up with the PCF. At time t4 the PCF confirms GRE tunnel setup with the BSC. At time t5, the PDSN uses IGMP or MRP to join amulticast group. Note that the initial processing may implement IGMP tothe first router. The process forms the MC tree between the CS and thePDSN. At this point the BSC is setup to receive BC messages via MC IPfrom the BC CS for the given HSBS channel.

According to one embodiment, for BC service processing, the CSconfigures an HSBS channel using a local mechanism. The CS uses the MCIP address to send the HSBS content. The HSBS configuration results inthe CS sending HSBS content to the corresponding MC group. The contentis sent in the format of IP packets having the source IP address of theCS and the destination IP address as a MC IP address.

The BSC then decides to add an HSBS channel on a given broadcastchannel. The broadcast channel is to be transmitted over a set ofcells/sectors. The mechanism in the BSC to add an HSBS channel to abroadcast channel is implementation-specific. One example of such amechanism is an interface that enables HSBS channel configuration on theBSC, such as an Operation Administration & Management (OA&M) interface.The BSC uses the local mechanism to setup the HSBS channel, usinginformation such as the HSBS_ID of the HSBS channel and the MC IPaddress corresponding to the HSBS content.

The BSC sends an A9-Setup-A8 message to the PCF. In the A9-Setup-A8message, the BSC sends A8_Traffic_ID parameter that contains among otherthings, the GRE key, and the IP address of the BSC entity thatterminates the A-8 connection for the HSBS channel. An additional field,IP_MulticastAddress, is added to the A8_Traffic_ID parameter. Theadditional field identifies an IP multicast address that is used by theCS to transmit the HSBS content. A new service option for HSBS serviceis used in the A9-Setup-A8 message.

Upon receiving the A9-Setup-A8 message from the BSC, the PCF is alertedthat the BSC wants to join an IP multicast group. If the PCF is alreadya member of the desired multicast group then no further action may benecessary to join the multicast group. Otherwise, the PCF sends an IGMPrequest to its multicast router to join the multicast group. Uponsuccessful IGMP setup, the PCF sends the A9-Connnect-A8 message back tothe BSC. The multicast route information propagates from the multicastrouter using multicast routing protocol to the upstream routers, throughPDSN all the way to the CS. This sets up a multicast path or tree fromthe CS to the PCF. The PCF achieves binding of GRE A8-Key, BSC IPaddress and IP Multicast address to properly tunnel IP multicast packetsto a BSC.

There are several multicast routing protocols used for multicast routingin an IP environment. The Distance Vector Multicast Routing Protocol(DVMRP) is specified in RFC 1075 by D. Waitzman, C. Partridge, S. E.Deering on Nov. 1, 1988. The Protocol Independent Multicast-Sparse Mode(PIM-SM) is specified in RFC 2362 by D. Estrin, D. Farinacci, A. Helmy,D. Thaler, S. Deering, M. Handley, V. Jacobson, C. Liu, P. Sharma, L.Wei in June 1998. There is also Multicast Open Shortest Path First(MOSPF), specified in RFC 1584 entitled “Multicast Extensions to OSPF.”By J. Moy in March 1994.

Continuing with FIG. 11B, a GRE connection is set from the BSC to thePCF, wherein a GRE tunnel set up message is sent, such as illustrated attime t1 of FIG. 11B. In the GRE set up message, the BSC sends aTraffic_ID parameter containing, the GRE key, and the IP address of theBSC entity terminating the connection for the HSBS channel. TheIP_MulticastAddress, is added to the Traffic_ID parameter. TheTraffic_ID parameter may include a variety of other information. TheIP_MulticastAddress identifies an IP MC address used by the CS totransmit the HSBS content.

In operation, the CS sends the HSBS content, e.g., BC message, to a MCIP address. The MC IP address is used in the destination address fieldof the IP packets. The multicast router routes the packet to memberPDSN(s). Note that the multicast group membership is established earlierusing IGMP and MC routing protocol. After header compression (if it isperformed), PDSN places each packet in an HDLC frame. The HDLC frame isencapsulated in a GRE/IP packet. The PDSN sets the Key field of the GREpacket to the destination MC IP address of the encapsulated IP packet.The GRE packet is appended with the 20-byte IP packet header havingsource address field of the PDSN IP address and destination addressfield of the same MC IP address as the encapsulated packet. The PDSNsends the encapsulated HDLC frame to the member Multicast router(s). Allmulticast member PCFs receive the MC packets. The need for sequencing isdue to the header compression in the PDSN. The GRE includes sequencenumbers identifying packets. The GRE sequence numbers ensure in-orderdelivery of packets.

Multiple BSCs may be used to broadcast a same HSBS channel to cover acertain geographic area. In this case, the HSBS channel is associatedwith a specific frequency. To facilitate autonomous soft hand off,transmission of the Fundamental Broadcast Service Channel or F-BSCH issynchronized in a geographic area. This allows for combining ofbroadcast packets at the mobile station. According to one embodiment theMC tree includes a leaf referred to as an “anchor BSC” that duplicatesthe broadcast content to the secondary BSC. The anchor BSC willduplicate and send the HDLC frames to any secondary BSC(s) over aspecific interface, wherein the transmission to the secondary BSC(s)have a constrained delay.

FIG. 12 illustrates a method of processing of a MC message istransmitted to a MC group. The process is for a Group Call service,wherein the message to be broadcast may originate with a user in thesystem. The group call allows a user to provide point-to-multipointtransmission. One user in the group transmits a message for multipleintended recipients. The process 600 begins at step 602 wherein the CSdetermines a start time for the MC message. The MC group subscribersregister with the BSC at step 604. At step 605 the BSC sends a set upmessage to the PCF. The set up message initiates the formation of a GREtunnel between the BSC and PCF, while also alerting the PCF that the BSCis part of the Group Call. The process builds an MC tree at step 606between the PDSN and the PCF(s). The process then builds an internal MCtree form the PDSN to the CS at step 608. Once the MC trees are set upthe source sends the MC message addressed to the MC IP address at step610. The message travels through the trees at step 612. The PCFtransmits the MC message to the BSC via a UC connection at step 614. TheBSC then forwards the MC message to the group members within thecorresponding geographical area at step 616.

Note that for a MC message transmitted to a MC group, the group membersmove within the communication system. When a group member moves to alocation that is not registered within the MC tree or is not part of theMC message transmission, the group member registers with the BSC of thenew location. During a group call, the group member will be monitoringthe frequency assigned to the BC channel used for the group call. Byregistering with a new BSC, the group member provides the system withthe frequency of the BC. The system is then able to page the groupmember of an incoming call. Once the group member registers with a newBSC, the system creates a new MC tree that includes the new BSC.

Alternate embodiments may apply the methods discussed hereinabove toalternate BC services, wherein a point-to-multipoint transmission isused. The use of MC trees formed by the leaves or termination pointsregistering with successive routers provides a convenient and dynamicmethod of avoiding redundancies in the communication system.Additionally, the use of MC trees provides increased scalabilityreducing the amount of infrastructure required for expanding thenetwork.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the embodiments disclosed herein may be implemented aselectronic hardware, computer software, or combinations of both. Toclearly illustrate this interchangeability of hardware and software,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system. Skilled artisans may implement the describedfunctionality in varying ways for each particular application, but suchimplementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such the processorcan read information from, and write information to, the storage medium.In the alternative, the storage medium may be integral to the processor.The processor and the storage medium may reside in an ASIC. The ASIC mayreside in a user terminal. In the alternative, the processor and thestorage medium may reside as discrete components in a user terminal.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

1. An infrastructure apparatus for providing broadcast transmissionsfrom a wired communication network to a wireless communication network,the infrastructure apparatus comprising: means for establishing one ormore secure tunnels to communicate with one or more infrastructureentities of the wireless communication network; means for joining amulticast tree associated with the wired communication network; meansfor receiving a multicast transmission over the multicast tree, whereinthe multicast transmission comprises an encapsulated packet; and meansfor transmitting the encapsulated packet over the one or more securetunnels.
 2. The infrastructure apparatus of claim 1, further comprisingmeans for receiving requests from the one or more infrastructureentities to join the multicast tree.
 3. The infrastructure apparatus ofclaim 1, wherein the multicast transmission identifies its source as anintermediate node and the encapsulated packet identities its source as aselected content source of the wired communication network.
 4. Anapparatus for providing broadcast transmissions from a wiredcommunication network to a wireless communication network, the apparatuscomprising: circuitry configured to establish one or more secure tunnelsto communicate with one or more infrastructure entities of the wirelesscommunication network; join a multicast tree associated with the wiredcommunication network; receive a multicast transmission over themulticast tree, wherein the multicast transmission comprises anencapsulated packet; and transmit the encapsulated packet over the oneor more secure tunnels.
 5. The apparatus of claim 4, wherein thecircuitry is further configured to receive requests from the one or moreinfrastructure entities to join the multicast tree.
 6. The apparatus ofclaim 4, wherein the multicast transmission identifies its source as anintermediate node and the encapsulated packet identifies its source as aselected content source of the wired communication network.
 7. A methodfor providing broadcast transmissions from a wired communication networkto a wireless communication network, the method comprising: establishingone or more secure tunnels to communicate with one or moreinfrastructure entities of the wireless communication network; joining amulticast tree associated with the wired communication network;receiving a multicast transmission over the multicast tree, wherein themulticast transmission comprises an encapsulated packet; andtransmitting the encapsulated packet over the one or more securetunnels.
 8. The method of claim 7, further comprising receiving requestsfrom the one or more infrastructure entities to join the multicast tree.9. The method of claim 7, wherein the multicast transmission identifiesits source as an intermediate node and the encapsulated packetidentifies its source as a selected content source of the wiredcommunication network.
 10. A computer program product for providingbroadcast transmissions from a wired communication network to a wirelesscommunication network, the computer program product comprising: acomputer-readable medium encoded with instructions executable to:establish one or more secure tunnels to communicate with one or moreinfrastructure entities of the wireless communication network; join amulticast tree associated with the wired communication network; receivea multicast transmission over the multicast tree, wherein the multicasttransmission comprises an encapsulated packet; and transmit theencapsulated packet over the one or more secure tunnels.
 11. Thecomputer-readable medium of claim 10, further encoded with instructionsexecutable to receive requests from the one or more infrastructureentities to join the multicast tree.
 12. The computer-readable medium ofclaim 10, wherein the multicast transmission identifies its source as anintermediate node and the encapsulated packet identifies its source as aselected content source of the wired communication network.